why michelle obama is going viral tonight. >>> and good evening. i'm dan harris. we'll get to david muir in iran in just a moment. >>> but we're going to start tonight with the breaking news out of florida. a treacherous finale to a race at the daytona international speedway. cars colliding, getting tossed around like toys. pieces of cars flying over a fence, injuring at least a dozen people, many of them fans. abc's linzie janis on the story. >> reporter: one driver sparked a dramatic crash on the daytona track. >> and contact! and a terrible crash coming to finish. >> reporter: sending his car spinning into the wall and another going airborne. parts of the 12 cars involved in the crash, slide through the fence, into the stands, hitting and injuring spectators. so far, 15 people have been taken to the hospital. the drivers are all okay. now, take a look again. the driver out front is regan smith, he tries to prevent his opponent, the car directly behind him, from trying to break out in front. triggering the giant crash, sending the car of kyle larson into the air